Two of the coldest places on the planet are the north and south poles.  Polar bears have lived in the Arctic since the ice age.  Penguins have lived in the land that is now Antarctica for even longer.  This book is packed with fascinating information about these two animals living in extreme conditions.  Almost every sentence is a intriguing fact.  There is an activity for understanding the effectiveness of blubber, or a layer of fat, for conserving heat.  A list of resources used for writing the three chapters precedes the glossary, index, other books to read, and internet addresses.  Well researched resource for upper elementary and middle school libraries.